The invention relates to a communications line control system and more specifically relates to a control system for controlling and recording the use of long-distance communication circuits.
Until recently, PBX or CENTREX users were limited to dial access and manual access through an operator to long-distance or bulk facilities. In a dial access system, the users completed the call or, if all of the bulk facilities were busy, obtained blocking, i.e., trunk busy signals. In a manual system, an operator placed the call, generally after toll ticketing it manually, over bulk facilities or long distance and, if requested, manually queued the call by calling back the user when the appropriate bulk facility was available. More recently, the telephone company has introduced various modes of flexible route selection systems (FRS) whereby a user's call may be automatically processed on a number of different types of bulk facilities, depending on the route selected by the user. In order to enhance the use of the bulk facilities, the concept of automatic queueing of calls by holding onto their line for a specific time, generally 30 to 60 seconds, was implemented. Such automatic queueing allowed more efficient use of the bulk facilities and thereby lowered the cost per minute to the user. However, in each of these cases, cost is generally traded off with service, as will be explained.
A manual system is inefficient with respect to obtaining access for a user to a particular desired bulk facility because the operator controls the call and it is somewhat inefficient with respect to utilization of the bulk facility per se. In a manual system, the operator must note that the desired facility has become available, generally by observing a light, and then call back the user before placing or dialing the call on the bulk facility. During this interim period, the facility is not used, thus rendering the system inefficient.
Dial access systems, wherein the user dials the facility directly on a hit-or-miss basis, are inefficient. The user often obtains a busy signal and, since no indication is provided as to when the facility will become available, the line often sits idle while the user waits.
Dial access systems can be provided with an alternative method of accessing bulk facilities, commonly termed "hold-on" queueing, whereby the user waits for a bulk facility to become available with his telephone off-hook. In such systems, the user is either passed immediately onto a line or waits, generally for up to 60 seconds, for a line to become available. If no line in the desired bulk facility becomes available during that period, the call is overflowed to other more costly facilities or direct distance dial trunks (DDD). While hold-on queueing increases the likelihood of the user gaining access to the bulk facility, as compared to dial access systems without hold-on queueing, the user is often overflowed before a bulk facility is accessed. The average duration of a business telephone call is on the order of five (5) minutes. Accordingly, the likelihood of a bulk facility becoming available during the 60 second hold-on period is relatively small. Larger hold-on periods are impractical in that the user's line is tied up during the hold-on period.
The longer the user is willing to wait, the greater the likelihood that a particular bulk facility, line or group of lines will be available for placing the call. Thus, it is desirable to provide a call-back system wherein the user can wait for a relatively long period of time for a facility to become available, without tying up his line for that period or requiring that the facility stand idle while the user or operator redials the called number.
A call-back system in accordance with the present invention provides the automatic calling back and placing of calls through electronic means and is able to store the called number so that neither the user nor operator has to redial the called number when the bulk facility becomes available and, further, wherein the user's line is not tied up during the waiting period. The caller enters the least-cost routing system by dialing an access code through his PBX or CENTREX. After obtaining a system dial tone, entering an account number (if required), the long distance number (10 digits, speed or tie line) is dialed. The computer checks the least-cost routing table to see if an appropriate line is available. If a line is available, the call is automatically outdialed, but if one is not available, the caller is given an All Trunks Busy signal and then return of the system dial tone. The caller then enters the extension of the PBX or CENTREX to be called back. The computer processor stores the call-back number and the long-distance number and places the call in an appropriate queue, in accordance with a predetermined priority classification of the user or call.
The call continues to move up in the queue and when the appropriate line becomes available, the computer controls the system to dial out the extension of the caller through the PBX or CENTREX. When the caller goes off-hook, the system then grabs the available line (which has been saved during the call-back period) and automatically places the call on the bulk facility for the caller.
If the caller is using his telephone at the time of call-back, the system detects the busy indication and places the call-back in queue and will continue to try until the call-back can be placed.
Obviously, during the waiting period, the caller can accomplish other work and the system operates in the most efficient and economical manner by "holding" the calls until the correct line is available.
It is most important to recognize that the smaller the group of bulk facilities, the more important it is to have a long waiting time in order to maximize access by a particular user to the bulk facility. As an example, if there is a single line group (like an intrastate line or an FX line) and the users of the calling company average 5 minutes per telephone call, it becomes apparent that the likelihood of obtaining the single line becomes greater, if it is in use, the longer the caller waits. If the waiting period is 30 or 60 seconds for the 5 minute call, the chances of getting the line are small, about 60/300 seconds or 20%, depending on when the caller enters the system. If the caller has automatic call-back capabiility, as in a system in accordance with the present invention, he may wait up to the predesignated time, usually 10 minutes and the likelihood of having the call placed on the bulk facility is excellent. This system is, in fact, about 20% more efficient than an automatic queueing system using hold-on and, because of the automation of placing the calls and knowing when the line is available, about 12% more efficient than operator queueing.
Copending application Ser. No. 793,428, "Telecommunications Management and Control System", filed on May 3, 1977 by the present inventors, relates to a method and apparatus, hereinafter referred to as the "least cost routing system", for switching long-distance telecommunications circuits wherein a central processing system is coupled to each of a plurality of remote satellite switching units. Each remote satellite switching unit includes a circuit routing matrix for connecting a local station to a selected long-distance line which may, for example, be a local trunk line, bulk rate lines such as WATS, foreign exchange or tie lines or lines between remote units. The remote satellite switching unit also includes a microcomputer system for detecting the status of outgoing lines from a PBX or CENTREX and the destination of a requested call. This information is transmitted to the central processing system which, in turn, selects the least expensive line at any given time for transmitting the long-distance call. The least expensive available line information is transmitted back to the microcomputer system which provides command signals to the circuit routing matrix to connect the requested call to the selected outgoing long-distance line. The central processing system compiles a record of the party placing the call, the long-distance line used, the time duration of the call and line utilization of the system, and further observes the status of the remote unit, etc. to compute a periodic account statement for the subscriber.
The present invention is embodied in a similar system. It should be appreciated, however, that, in the present invention, the circuit routing matrix and outgoing line status detection may be incorporated into the central processor (computer) rather than residing in remote satellite switching units. The disclosure of such aforementioned copending application Ser. No. 793,428 by the present inventors is herein incorporated by reference.